Filter cartridge assembly

ABSTRACT

A filter cartridge assembly ( 10 ) including respective disposable elements ( 11 ) positioned either side of a three part reusable flow through spacer elements ( 12 ), the spacer elements ( 12 ) comprises three parts, opposed support sections ( 19 ) and ( 20 ) and an outer locator ring ( 21 ). The support sections ( 19 ) and ( 20 ) have filtrate flow through passages ( 22 ) and abutment flanges ( 23 ) which abut to provide radial flow through passages ( 24 ). Each of the supports ( 19 ) and ( 20 ) include circular ridges ( 25 ) and ( 26 ) at the inner and outer peripheral edges designed to push into the paper roll ( 16 ) while O-rings ( 27 ) and ( 28 ) provide seals between the supports ( 19 ) and ( 20 ) and the ring ( 21 ) and the outer body ( 13 ) of the respective elements ( 11 ).

TECHNICAL FIELD OF THE INVENTION

THIS INVENTION relates to a filter cartridge assembly and in particular,but not limited to, a filter cartridge suitable for filtering oil orfuel.

BACKGROUND TO THE INVENTION

Filters are known that employ an outer filter body holding disposablefilter cartridges, the outer body usually has a cylindrical housing anda cap, a coaxial return pipe usually has a threaded end and the capscrews onto the threaded end to clamp the cartridges in operativeposition in the housing. Liquid flows though an inlet, through filtermedia in the cartridges and out through the return pipe. Spentcartridges are simply exchanged with new ones. Typical cartridges areknown that are made from a paper roll held in a plastics or metalcylinder. An example is described in WO/0037232. There are variousalternative constructions and flow modalities used.

European patent application No. P 0 556 506A1 describes a modular filtersystem consisting of cartridges made from a tightly wrapped paper filtermedia retained in a plastic casing. The plastic casing has integrallyformed grate-like configuration on its top and bottom surfaces to allowfluid to enter an exit the filter. The casing is also dimensioned toclosely surround the paper media. The filter cartridges are stackablewithin the filter housing which can retain a plurality of cartridgesthereby increasing the capacity of the filter. Each casing is made fromidentical top and bottom halves where the cylindrical walls cliptogether around the paper roll. When two cartridges are used the gridlike top of one cartridge a butts the grid-like bottom of the other sothat liquid flows from one cartridge to the next in series. Thus liquidflows one way, from one end only and is recovered out the other end. Thecentral pipe in this case is an inlet pipe rather than a return pipe.

Other arrangements are known where liquid flows simultaneously into thefilter in opposite directions and is recovered centrally, see forexample Australian Patent 729523 and U.S. Pat. No. 4,792,397.

Australian Patent 729523 and WO/0037232 describe an injection mouldedfilter cartridge filled with a paper roll filter media. Unlike thecartridge of European patent application No. P 0 556 506A1, thecartridge is open ended and does not employ grate-like ends. This allowsa press to be used to insert paper rolls under pressure. In onecartridge opposite ends of the cartridge are completely open so thecartridge is effectively a tube with two back-to-back paper rollsseparated by gauze providing a return flow path. The paper rolls have acentral bore made of cardboard for a return pipe. Thus when thecartridge is clamped inside a filter container liquid flows from aninlet in the container in both ends of the cartridge, through the paperrolls and is recovered by flowing out the ends of the paper rollsthrough a common return path formed by the gauze to the central returnpipe. The gauze separates the confronting ends of the rolls and providesa flow path for the filtered liquid. Gauze is also used in thearrangement of Australian patent 659793 to separate two paper rolls in ametal cannister.

In U.S. Pat. No. 4,792,397 back-to-back paper rolls are used in asimilar arrangement Australian Patent 729523 and WO/0037232 exceptinstead of gauze being used to separate the rolls U.S. Pat. No.4,792,397 uses a specially made fluid collector between the rolls. Thefluid collector has closely spaced concentric ridges projecting fromopposite sides of a substantially flat portion, pressure equalisationholes pass through the flat portion. The ridges push into the paperrolls on opposite sides of the collectors. Gaps in each ridge allowsradial return flow to the central return pipe.

In Australian patent 650176 a metal canister is provided with end walldepressions to improve radial return flow. In Australian patentapplication 59243/00 a fluid collector is provided in an end wall of thehousing, the fluid collector has lands in the form of sectors of acircle separated by radial flow passages.

The prevailing design criteria adopted in all these instances is tosupport the paper across its ends in an effort to maintain the returnflow and minimise blockages that might impede flow as the papercollapses. Since the filters are pressurised as the filter media agesand becomes loaded it may distort in the region of the return flowleading to blockages. The gauze may become depressed by the paper beingforced across the gap. Thus in the above examples it is usual to providea substantial amount of support at the end of the paper roll with fluidcollectors with relatively large flow paths being preferred to wiregauze.

The present invention adopts a completely different approach to theproblem of supporting the roll while maintaining greater efficiency ofreturn flow across the filter.

OUTLINE OF THE INVENTION

In one aspect the present invention resides in a filter cartridgeassembly assembled form two disposable filter elements and spacer meansholding the filter elements in separate spaced apart relationship, eachfilter element comprising an outer housing containing an annular papercore, characterised in that the spacer means comprises a reusableback-to-back filter element support means with through holes for flow offiltrate flowing through the annular paper core into the spacer means,the spacer means having cross flow passage means within said spacermeans for inward flow of said filtrate for return through a return pipe,the spacer means being supported by a reusable outer locator ring inwhich the spacer means is located and which extends in oppositedirections outside a peripheral marginal portion of the housings of therespective disposable filter elements.

Typically, the outer ring includes O-ring holders to hold sealing ringswhich seal the locator ring against the spacer and the peripheralmarginal portions of the of the housings of filter elements.

Preferably, the spacers include upstanding outer ridges that penetrateperipheral portions of the paper core and there being on opposite sidesof the spacer means a plurality of ridges that hold the paper roll andsupport it, defining transverse flow channels leading to said throughholes promoting flow along the spacer in the channels to the spacedthrough holes.

Preferably, the spacer is made from two disc members havingcircumferentially spaced mating abutments, gaps between the abutmentsdefining return flow through passage means.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the present invention can be more readily understood andbe put into practical effect, reference will now be made to theaccompanying drawings which illustrate a preferred embodiment of theinvention and wherein:

FIG. 1 is a section through a filter cartridge assembly according to theinvention;

FIGS. 2 and 3 are respective plan and section views of a spacer andlocator ring as assembled; whilst

FIG. 4 is a detailed view of a typical outer circular ridge.

METHOD OF PERFORMANCE

Referring to the drawings and initially to FIG. 1 there is illustrated afilter cartridge assembly 10 comprising respective disposable filterelements 11 positioned either side of a three part reusable flow throughspacer means 12, each of the filter elements 11 comprises a hollowcylindrical plastics outer body 13 which has internal ribs 14 spacedalong its inner surface 15 to provide an anti tracking functioninhibiting flow along the interface between annular paper filters 16 andthe outer body 13.

Annular paper roll filters 16 have been pushed, under compression, intothe plastics outer bodies 13 of the respective elements 11. Each of thepaper filters 16 has a central cylindrical cardboard core 17. Thus acomplete passage is formed through the assembly at 18 so that a filtratereturn pipe can be inserted through and also used to provide inconjunction with a filter housing (not shown) a clamp against oppositeends of the assembly to clamp the assembly together.

The spacer means 12 comprises three cast metal parts, opposed supportsections 19 and 20 and an outer locator ring 21. The support sections 19and 20 have filtrate flow through passages 22 and abutment flanges 23which abut as shown providing radial flow through passages 24. Thismeans that filtrate can flow through the paper filter 16, through theflow through holes at 22 and their associated surface flow channels andthen radially through the apertures 24 to a return (not shown). Each ofthe supports 19 and 20 include circular ridges 25 and 26 at the innerand outer peripheral edges designed to push into the paper roll 16 whileO-rings 27 and 28 provide seals between the supports 19 and 20 and thering 21 and the outer body 13 of the respective elements 11.

Whilst the above has been given by way of illustrative example of thepresent invention many variations and modifications thereto will beapparent to those skilled in the art without departing from the broadambit and scope of the invention as set out in the appended claims.

What is claimed is:
 1. A filter cartridge assembly assembled from twodisposable filter elements and spacer means holding the filter elementsin separate spaced apart relationship, each filter element comprising anouter housing containing an annular paper core, characterised in thatthe spacer means comprises a reusable back-to-back filter elementsupport means with through holes for flow of filtrate flowing throughthe annular paper core into the spacer means, the spacer means havingcross flow passage means within said spacer means for inward flow ofsaid filtrate for return through a return pipe, the spacer means beingsupported by a reusable outer locator ring in which the spacer means islocated and which extends in opposite directions outside a peripheralmarginal portion of the housings of the respective disposable filterelements.
 2. A filter cartridge assembly according to claim 1 whereinthe outer ring includes O-ring holders to hold sealing rings which sealthe locator ring against the spacer means and the peripheral marginalportions of the of the housings of filter elements.
 3. A filtercartridge assembly according to claim 1 wherein the spacer meansincludes upstanding outer ridges that penetrate peripheral portions ofthe paper core and there being on opposite sides of the spacer means aplurality of ridges that hold the paper roll and support it, definingtransverse flow channels leading to said through holes promoting flowalong the spacer in the channels to the spaced through holes.
 4. Afilter cartridge assembly according to claim 1 wherein the spacer meansis made from two disc members having circumferentially spaced matingabutments, gaps between the abutments defining return flow throughpassage means.
 5. A filter cartridge assembly according to claim 1wherein the outer ring includes O-ring holders to hold sealing ringswhich seal the locator ring against the spacer and the peripheralmarginal portions of the of the housings of filter elements, the spacerincluding upstanding outer ridges that penetrate peripheral portions ofthe paper core and there being on opposite sides of the spacer means aplurality of ridges that hold the paper roll and support it, the ridgesdefining transverse flow channels leading to said through holespromoting flow along the spacer in the channels to the spaced throughholes.
 6. A filter cartridge assembly according to claim 1 wherein theouter ring includes O-ring holders to hold sealing rings which seal thelocator ring against the spacer means and the peripheral marginalportions of the of the housings of filter elements, the spacer meansbeing two disc members having circumferentially spaced mating abutments,gaps between the abutments defining return flow through passage means.7. A filter cartridge assembly according to claim 1 wherein the spacermeans includes upstanding outer ridges that penetrate peripheralportions of the paper core and there being on opposite sides of thespacer means a plurality of ridges that hold the paper roll and supportit, the ridges defining transverse flow channels leading to said throughholes promoting flow along the spacer in the channels to the spacedthrough, the spacer means comprising two disc members havingcircumferentially spaced mating abutments, gaps between the abutmentsdefining return flow through passage means.